Development of antifungal gelatin-based nanocomposite films functionalized with natamycin-loaded zein/casein nanoparticles

In this study, natamycin-loaded zein/casein composite nanoparticles (Nata-Z/C NPs) were fabricated and incorporated into gelatin film to improve the film's physicochemical and antifungal properties. The mean particle diameter (MPD) and zeta potential (ZP) values of the Nata-Z/C NPs were characterized by dynamic light scattering (DLS) with 68.5 ± 1.2 nm and −33.1 ± 0.8 mV, respectively. The Nata-Z/C NPs were well dispersed in the gelatin film and improved its mechanical properties, including the tensile strength (from 30.5 ± 3.2 MPa to 51.4 ± 3.0 MPa) and percentage elongation at break (from 0.225 ± 0.087 to 0.685 ± 0.103). The NPs as hydrophobic filler also improved the water barrier properties to 0.335 × 10−9 gˑm/m2ˑPaˑs and water contact angle to 122.55 ± 1.54° of the gelatin film. The possible interactions between the Nata-Z/C NPs and gelatin were studied by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. The sustained release of natamycin from the film was achieved by its encapsulation, and the release kinetics were assessed with the Avrami model. Furthermore, the nanocomposite films exhibited strong antifungal activities against Aspergillus niger, Botrytis cinerea, and Penicillium citrinum. This study revealed that the Nata-Z/C NPs could be used as both nanofillers and functional additives to improve the physicochemical and bacteriostatic properties of gelatin films.